The turbine housing has a high heat capacity. Arranging such turbine housing on an upstream side of an exhaust-gas purification catalyst can interfere with warming the catalyst. In view of a recent trend of a tighter control on exhaust emission, it is important to reduce heat capacity by making the housing from a sheet metal to achieve a thinner and lighter housing so as to improve catalyst purification capability with activated catalyst.
In the case of the sheet-metal turbine housing, the sheet-metal part is thin and has low strength. Thus, it is necessary to provide support columns between a member on the side of the bearing housing in which the bearing is provided to support a rotation shaft of a turbine rotor blade and a member on a gas exhaust side so as to link and fix the members to each other. However, the support columns are arranged transversely across a flow path of the exhaust gas on an outer peripheral side of the turbine rotor blade. The support columns interrupt the gas flow, which leads to decrease in efficiency and a performance of a supercharger.
Patent Literature, JP2006-527322A discloses a spacer 01. As shown in FIG. 11, an exhaust gas turbine 02 is configured such that inside a housing 04 having a scroll shape and covered by an outer shell 03, a bearing ring 05 for an adjustable guide vane and a molded casing 07 are linked by the spacer 02 provided therebetween. The spacer 01 is arranged transversely across a flow path 09 of the gas into the turbine rotor blade in a radial direction.
Another sheet-metal turbine housing as a related technique is disclosed in Patent Literature 2, JP2008-57448A and Patent Literature 3, JP2003-536009A.